Resistance unit



March l0, 1931. 1 J, MUCHER 1,795,961

RESISTANCE UNIT Filed Nov. 22. 1928 2 Sheets-Sheet l INVENTOR f/zw 4 BY Wfww.

ATTORNEY March 10, 1931. 1. J. MUCHER 1,795,951

' RESISTANCE UNIT Filed Nov. 422, 1928 2 Sheets-Sheet 2 lNvENToR BY 932W@ ATTORNEY1 Patented Mar. 1o, 1931 1,795,961

UNITED STATES PATENT OFFICE JOHN J. MUCHER, F BROOKLYN, NEW YORK RESISTANCE UNIT Application led November 22, 1928'. Serial No. 321,114.

This invention relates to resistance units, Figure 7 is a fragmentary sectional view and has for an object to provide an improved showing the lower part of the casing, but construction wherein an extremely sensitive showing an additional, modified arrangement and accurate instrument is produced, and one of electrodes;

Which avoids extraneous influences caused by Figure 8 is a sectional view showing a 55 moving contacts. modified form of the invention, wherein the Another object of the invention is to procasing is of metal; vide a resistance unit wherein the electrodes Figure 9 is a top plan view of the resistor terminals are all stationary and where a ance unit casing shown in Figure 2, but with 10 compressible resistance medium is used to lnodiied form of terminal or electrode; eo connect the terminals, the arrangement being Figure 10 is a sectional view through suoli that the resistance medium may have its Figure 9 on the line 10-10; density varied at will to vary the resistance Figure 1l is a plan view of a modified form provided between the respective terminals. Of Shaft-retaining disk;

Another Object 0f the invention is t0 pro- .Figure l2 iS 1, plan View Of a further mOCli- 5 vide a resistance unit wherein the electrodes 58d forni of Shaft-retaining disk; or terminals are surrounded by a resistance Figure 13 is a fragmentary sectional view medium or arranged in contact therewith SlOWIlg the lower part of the casing illusy with parts associated with the resistance tinted in Figure 10 but with a modified form medium, whereby the same may have its 0f electrode o r terminal; 7o density varied without producing noises in a Flgure 14 1S a View similar to Figure 13 telephone or radio circuit when the unit is but showing a further modified form of elecused on such a circuit. trodes;

An additional object is to provide a resist- .Flglgre l5 1S a View Similar to Figure 14 ance unit for producing a desired resistance disclosing a diiferent arrangement of elec- 75 in an electric circuit with the parts so ar- IOdeS; ranged that the terminals and resistance FlgllIQ 16 1S 21 View Slmlal' t0 Figure 15 medium are all Substantially Stationary but but showing a further arrangement and modisubject to a compressor for varying the action ClOIl Of eleCtlOdeS- of the resistance medium, which action takes RGQ-Illng to. the accompanying drawings so place Without producing my movement 0n by numerals, l indicates a casing or container the terminals but; varying the resistance formed preferably of insulating material, as medium in Connection with the terminals, for instance, porcelain, phenol condensation In the accompanying drawings,- product or other suitable material which will Figure lis a top plan View of the resistance withstand the desired usage. If desired, this e5 unit disclosing an embodiment of the invencasing could be made of metal or other matetion; rial, but if made of metal an insulated lining Figure 2 is a sectional view through Figure is necessary and certain parts must be insulat- 1 on the line 2 2; ed. By providing the casing l of insulation a Figure 3 is a perspective view of a shaftsimple, strong construction is presented and 9o retaining disk embodying certain features of the casing acts both in the capacity of a conthe invention; tainer and an insulating structure. A num- Figure 4 is a sectional view through Figure ber of anchoring bars or rivets 2 are provided 2 on the line H; in the walls of the casing, the walls being Figure 5 is a perspective view of the conithickened at 8 to accommodate these anchor- 95 presser remove the holding rivets being ing bars. As illustrated in Figure 2, the rivomitted; ets or anchoring bars 2 extend through the Figure 6 is a perspective view of an adjustcover 4 and through the shaft-retaining disk 'f ing shaft embodying certain features of the 5, after which they are upset or riveted, as invention; clearly shown in Figure 2. Extending 100 through the cover 4 is a sleeve 6 having a threaded end, whereby the device may be connected to a support, said sleeve having an enlarged flange 7 arranged beneath the raised part 8 of cover l. This sleeve provides a bearing for the adjusting shaft said shaft having a smooth portion at the outer end for receiving a knob, if desired, an annular groove 10 for receiving certain parts of the disk 5 and a threaded portion or section 11 coacting With threads 12 in the plate of the compresser 11i. rllhe compresser 14E is formed with a top plate 13, as shown in Figure 5, said plate having suitable notches 15 for accommodating the thickened portions or beads 3. This arrangement is carried out throughthe fibrous packingdisk 16, whereby the compresser cannot rotate but may move toward and from the bottom 18. The disk 16 may be made from asbestos or other desired libre and is tightly clamped to the plate 13 by suitable rivets 19, said rivets having one end embedded in the bre disk 16, the rivets being positioned to extend through the plate 13. The embedded ends of t ie rivets are preferably covered by a suitable dielectric cement. The plat-e 13 is preferably of appreciable thickness so as to stand Whatever pressure may be exerted thereon for compressing` the resistance medium 21 which may be any granular resistance substance, as for instance, a mixture of mica and graphite. rlhis particular m 1'ure is desirable because it is rather resilient and yet provides a conducting path for electricity, the degree of conductivity being in proportion to the density of the medium. This density is varied by moving the compresser 1li toward or from bottom 18. Granular matter of this kind or other desired kinds will, when lei alone for an appreciable time, assume substantially the same. quality or degree orf-'resistance throughout, but When the compresser 14 is moved away from the bottom 18 the portion or layer ot resistance n'iedium 21 further from the bottom 18 vvill expand First and gradually later the central portion will expand and inally the layer nearest the bottom 18 will expand. For this reason andfor others including the desirability of'having stationary electrodes the construction shown in Figure 2 has been provid'- ed, whereby the terminals or electrodes 29 and 23 entend-through bottom 18 and are turned over for forming Contacty plates 211 and 25 embedded in the upper surface or" bottom 18 but always-in contact With the resistance medium 21. As the compresser 1li moves away from bottom 18 or toward bottom 18 no change in the contactv With members 24 and 5 will occur, as these members continually contact With the resistance medium so that there Will be no loose motion therebetween.

lt Will thus be seen that a device is provided wherein terminals are used continually in conmovement in adjusting or varying the resistlance Will not disturb the Contact of the electrodes, nor Will there be any loose motion between the parts. rllhis is very desirable Where the device is used in a telephone or radio circuit, as any loose motion or variation in resistance may produce undesired sound or other condition in the circuit. changing the pressure on the resistance medium the density is varied, and consequently, the resistance is varied. This is done Without changing the distance between the electrodes and Without providing any movable or rubbing contacts the circuit. ln addition to changing ror varying the resistance by changing the density of the medium 21, the resistance may be varied or controlled ay varying the distance of the electrodes and by varying the substance or lineness of the resistance material.

The arr or cont angement ot stationary electrodes a c nnecting resistance Which s action or resisting power varied i. il to a proposition of constructing a device which may use tivo electrodes, three electrodes or even more.

This principle also permits lthe electrodes to be variously positioned andr yet secure substantially indentical results. As shown in Figures 9 and 10 an arrangement has been disclosed which brings out this idea andV inr these figures three contacts have been shown., althoughif desired, more contacts could be shown or the contacts could'be diiierently arranged, as for instance, instead of the central contact 26 being midway between' the contacts 27 and 28 it could be arranged nearer one contact than the other. 'This arrangement permits a circuit to be used includingV only contacts 27 and 28 and at the same time a circuit including contacts 28 and 26 or a circuit including contacts 26 and 27.

In Figures 11 and 12 modified forms of shaft-retaining platesA are disclosed, Figure 12 showing a plate-5 having a slot 29, Whereby it may accommodate the neck 10 in shaft 9.k Figure 12 shows a disk or plate 5 having a comparatively large opening 30 merging into a slot 31 of a size to nicely accommodate neck 10. Opening or aperture 30 must, of course, be large enough to accommodate they upper part of the shaft 9, so that the shaft could be fed therethrough and then moved laterally so that the neck 10r Will lit in the slot 31. c

In Figures 7 andv 13 to 16 inclusive several modified forms of' terminals or electrodes have been presented and also modified arrangements, these structures illustrating how the device may be slightly varied toadapt itseltto varying' conditions. ln Figure 13 thel electrodes 32 and 33 entend into the medium 21 at the edges thereof and substantially centrally thereof.y These. electrodes arev spaced from the bottom ofthe casing, and

consequently, are surrounded on all sides with the medium 21. In Figure 14 a terminal 33 is provided similar to terminal 33 of Figure 13 and coacting with this terminal is an electrode or terminal 34 merely extending upwardly to substantially the center of the medium 21.

Figure 15 shows a slightly different arrangement of terminals 35 and 36, wherein the terminals project to a substantially central point within the medium 21 or the space to be occupied by this medium.

Figure 16 shows terminals 37 and 38 arranged substantially centrally of the bottom of the casing with rounded ends arranged substantially7 centrally of the space to be occupied by the resistance medium 21.

Figure 7 shows a further modified arrangement wherein the electrode or terminal 39 is embedded in the bottom of the casing and electrode 40 is resting on the surface of the bottom. It will thus be seen that in all forms of the invention the contacts or terminals are stationary and the resistance medium is substantially stationary but subject to compression, whereby the density may be varied, and consequently, the resisting action varied. In placing the resistance medium in the casing it may be placed loosely in the proper place and then compressed or it may be precompressed and then placed in the container. In providing the resistance material in either of the manners described, a resistance body is presented which is acted on by the com presser, as heretofore set forth In Figure 8 will be seen a further modiied form of the invention, wherein there is provided a casing 1 formed of metal and preferably formed of comparatively thin metal pressed into the desired shape. The upper part is provided with a flange 41 which may be turned over to secure the members 4 and 5 in place, if desired. The metal easing is feasible by reason of the fact that there is provided an insulating plate 42 in the bottom of the casing into which the terminals 43 and 44 are embedded. The terminals extend through suitable apertures 45 and 46 in the bottom of the casing. The resistance medium V21 is identical with that shown in Figure 2 and functions in the same manner. However, in arranging the terminals 43 and 44 they are positioned so that the distance between that part of the terminals in contact with the medium 21 will be less than twice the distance of the terminals from the side walls of casing 1. In this way the path of resistance will be less between the terminals than it will be between the terminals and the casing. By arranging the terminals in this manner the current will always pass through the medium 21 and consequently proper adjustment may be secured, as desired.

A resistance unit comprising a tubular casing of insulating material formed with a bottom, the walls of said casing having thickened portions at spaced intervals extending inwardly, an anchor embedded in each of said thickened portions and extending therefrom at one point, a cover plate held in position by said anchors, a pair of electrodes carried by said bottom, a granular resistance medium positioned in the casing and connecting said electrodes, a compressor positioned in said casing, said compressor having a plurality of notches in its periphery for accommodating said thickened portions whereby said compressor is held against in- 

